When simulating a compressor using Aspen, where is the polytropic index for polytropic compression entered?
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Everyone, when using Aspen to simulate compressors, where is the polytropic index for polytropic compression entered? How come I didn’t find it? It shouldn’t be necessary to enter any values, right? Also, with the same inlet conditions and compression ratio, polytropic compression should require less work compared to adiabatic compression, resulting in a lower outlet temperature, correct? But why is the outlet temperature higher according to the results obtained from my simulations using the polytropic method based on the ASME approach, as compared to those obtained using the isentropic method based on the ASME approach? Is the work done large? Thank you all first~
I first posted this thread in **, but no one responded in 5 days, so I copied it here. By accident, I copied the last sentence as well. I want to delete that last sentence, but I can’t do it; I click on edit, try to delete the last sentence, and save it, yet that sentence still appears. What’s going on?
It is entered in efficeincies: isentropic refers to isentropic efficiency, polytropic refers to polytropic efficiency, and mechanical refers to mechanical efficiency. Additionally, the efficiency value is entered by you yourself. If the simulated exit temperature is high, it might be because you didn’t enter a value; Aspen has a default efficiency value, which is around 0.7 I think
This post was last edited by hcer on 2016-6-13 09:45. The variability index does not need to be entered; it is determined by the properties of the substance itself, and it is also related to different compression methods. The actual compression polytropic index should be a variable value, which affects temperature and power and results in the final value differing from the theoretical one. I’m not entirely sure about the exact calculation method, but the built-in calculations are likely to be reliable.